The Lateral Flow Assay is a qualitative detection assay of residues in surface samples obtained from, for eample, production lines. The assay is also applicable for food samples. The assay is applied for the detection of small amounts of contaminations. Contaminations in food possibly elicit hypersensitivity in sensitive persons. Food production lines have to be free of residues to prevent these allergic reactions. The effectiveness of cleaning can be verified by using the lateral flow swabbing method.